Formation of Au Colloidal Crystals for Optical Sensing by DEP-Based Nano-Assembly

We report the observation of photoconductivity in gold colloidal crystal formed based on a dielectrophoresis (DEP) plus self-assembly technique. By using dielectrophoresis and capillary force, we have successfully confined the gold colloidal crystal formation between two electrodes and characterized the electronic properties of the crystal. We have found that the resistance of these crystals (in the MOmega range) has a linear relationship with the intensity of light and hence could serve as optical sensors. We envision that the process developed could be used to potentially fabricate extremely low-cost photo-detector efficiently.